Magnetic sensor and method of manufacturing the same

ABSTRACT

In a magnetic sensor, a lower terminal layer, a magnetosensitive layer, and a cover film are simultaneously patterned into substantially the same size. The opposing surface of the lower terminal layer, which opposes the magnetosensitive film is substantially superposed on one opposing surface of the magnetosensitive film. The opposing surface of the upper terminal layer, which opposes the magnetosensitive film is formed into a shape smaller than and included in the other opposing surface of the magnetosensitive film. This implements a magnetic sensor which uses a CPP structure and is yet readily processible and which includes a substantially accurate fine CPP structure in accordance with a desired output.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims priority of JapanesePatent Application No. 2000-044828, filed on Feb. 22, 2000, the contentsbeing incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to magnetic sensors in which asense current is applied to a magnetosensitive film to sense a change inexternal magnetic field through a change in resistance value (voltagevalue) of the film.

[0004] 2. Description of the Related Art

[0005] A magnetic sensor is conventionally used as arecording/reproduction magnetic head of a hard disk drive mountedprincipally in a computer. This conventional recording/reproductionmagnetic head senses an external magnetic field by means of an inducedcurrent generated in a coil. Recently, however, with increasing demandson high storage density and high processing speed, a magnetic sensorwhich senses an external magnetic field itself is often used. Thissensor uses the magnetoresistance (MR) effect. Furthermore, a magnetichead using the giant magnetoresistance (GMR) effect has appeared.

[0006] As the recording density of a hard disk drive increases, the1-bit recording area reduces, and the magnetic field generateddecreases. The recording densities of currently commercially availablehard disk drives are around 10 Gbits/in². However, the recording densityrise nearly doubles every year. This requires a magnetic head to controlfiner magnetic fields and sense smaller changes in external magneticfield.

[0007] At present, a spin valve type GMR film is used. This spin valveGMR film has a magnetic layer whose magnetization direction is fixed anda magnetic layer whose magnetization direction can freely change. Theelectrical resistance changes in accordance with the angle that themagnetization directions in these two magnetic layers make.

[0008] When this magnetic head is used, a sense current is made to flowin parallel with the film surface of the GMR film and sensed as a changein the resistance value (the voltage value: the output value) resultingfrom the external magnetic field. In this magnetic head having a CIP(Current In the Plane) structure in which a sense current is supplied inparallel with the film surface of the GMR film, the output value lowerswhen the element width (accurately, the effective core width) decreases.If the sense current amount is increased, a large output value isobtained by the Ohm's law. However, this sense current amount is limitedbecause the generation of heat or the like is unavoidable.

[0009] Also, the CIP magnetic head requires insulating layers betweenthe upper and lower magnetic shields. The distance between the magneticshields is (thickness of GMR film+thickness of insulating layer×2).Since the lower limit of the insulating layer thickness is presently 20nm, the distance between the magnetic shields is (thickness of GMRfilm+40 nm). If the lengths of recording bits on a recording medium areshortened, it becomes difficult to sense these bits. Therefore, thedistance between the magnetic shields cannot be reduced to 40 nm or lessat present.

[0010] From the foregoing, the CIP magnetic head using the spin valveGMR film can presumably achieve a recording density of up to 20 to 40Gbits/in². The upper limit is 60 Gbits/in² even when the latesttechnique using specular scattering is applied.

[0011] The recording density of hard disk drives is abruptly increasing,so a recording density of 80 Gbits/in² is probably required in 2002. Forthe above reasons, it is extremely difficult for the CIP magnetic headusing the spin valve GMR film to achieve a high recording density of 80Gbits/in² or more.

[0012] To solve these problems, a magnetic head which has a CPP (CurrentPerpendicular to the Plane) structure in which a sense current issupplied in a direction containing at least a component perpendicular tothe film surfaces of the MR film is regarded as promising. This magnetichead having the CCP structure shows a resistance change about twice thatof the CIP structure at room temperature, so a large output can beexpected. In this structure, the GMR film is not restricted to amultilayer GMR film. For example, a spin valve film or a coercive forcedifference type multilayer film can be used.

[0013] Another great advantage of the CPP magnetic head is that theoutput value increases as the sectional area (=core width of CIPstructure×height) of a portion of the GMR film through which a sensecurrent passes decreases. A high output value is obtained by decreasingthose surfaces of upper and lower terminals sandwiching the MR film,which oppose the MR film surfaces, by using this property.

[0014] The use of a magnetic head having a tunnel MR (TMR) structure inwhich an insulating layer is sandwiched between two magnetic layers issimilarly pursued. In this structure, a tunnel current passing throughthe insulating layer changes in accordance with the magnetizationdirection in each magnetic layer. Accordingly, the structure shows alarge resistance change and has a high output value. In the magnetichead having this TMR structure, a current flows in the order of magneticlayer→ insulating layer→magnetic layer. Additionally, the TMR structurehas advantages analogous to those of the CPP structure. Hence, the TMRstructure can be regarded as one type of CPP structure.

[0015] As described above, the CPP magnetic head is expected to replacethe CIP magnetic head. However, this CPP magnetic head has not been putinto practical use yet because it has the following several problems.

[0016] The following problems are particularly notable when the sizes ofthose surfaces of the upper and lower terminals, which oppose the GMRfilm surfaces, are decreased to further increase the output of the CPPstructure magnetic head.

[0017] (1) Element fabrication processes are complicated and requirehigh accuracy.

[0018] A series of processes of film formation, resist formation,photolithography, etching, and resist removal must be performed severaltimes. In particular, when the sizes of the opposing surfaces of theupper and lower terminals are to be decreased, it is essential to forminsulating layers corresponding to the two terminals. This formation isvery cumbersome and time-consuming. Additionally, in this case thoseportions of the opposing surfaces of these upper and lower terminals,which overlap correspond to a CPP portion which contributes to theoutput. Hence, an extremely high alignment accuracy is necessary inresist formation, and this makes a desired output very difficult toobtain.

[0019] (2) The characteristics are difficult to evaluate unless the sizeof the CCP portion is around 1 μm or on the order of submicrons.

[0020] If the size of the CCP portion is 3 μm or more, a voltage withrespect to a sense current is measured as a negative value owing to theinfluence of the current distribution, although this also depends on theelement structure, material, and the like. Under this influence, the MRratio takes a very large value around 3 μm. This prevents theapplication of the conventional evaluation standards.

[0021] (3) The characteristics are readily influenced by the quality ofelement fabrication processes.

[0022] Although this is also a problem of the magnetic head having theCIP structure, the problem is more notable in the CPP structure. When aGMR film and insulating layers are formed, the MR characteristicslargely change in accordance with the sectional shape and the conditionof burrs produced. This makes it difficult to specify the cause of adefective product.

SUMMARY OF THE INVENTION

[0023] It is an object of the present invention to provide a magneticsensor which uses a CCP structure to increase the output and is yetreadily processible and which can substantially accurately implement afine CPP structure in accordance with a desired output.

[0024] It is another object of the present invention to provide amagnetic sensor and a method of manufacturing the same which canaccurately control the shape and dimensions of a CCP portion to desiredfine values and can further increase the output and improve thecharacteristics.

[0025] According to the first aspect of the present invention, amagnetic sensor comprises a magnetically magnetosensitive film so as tofall within the area of the film surface.

[0026] According to the third aspect of the present invention, providedis a manufacturing method of a magnetic sensor in which amagnetosensitive film for sensing an external magnetic field isvertically sandwiched by a pair of terminals to apply an electriccurrent to the magnetosensitive film in a direction perpendicular to afilm surface of the magnetosensitive film. The method comprises thesteps of forming one of the terminals such that a surface of it isopposed to the magnetosensitive film so as to include the whole area ofthe film surface, forming the other of the terminals such that a surfaceof it is smaller in area than the film surface and opposed to themagnetosensitive film so as to fall within the area of the film surface,and the other of the terminals has a predetermined shape in a sectionperpendicular to the film surface and parallel to a magnetosensitivesurface, said shape having its width changing from one portion toanother, and polishing an end surface that is to serve as themagnetosensitive film, so as to control the width of the other of theterminals exposed on the end surface.

[0027] According to the fourth aspect of the present invention, providedis a read magnetic head comprising the magnetic sensor according to thefirst aspect for reading information stored in a magnetic recordingmedium.

[0028] According to the fifth aspect of the present invention, providedis a read/write magnetic head in which a read magnetic head comprisingthe magnetic sensor according to the first aspect for readinginformation stored in a magnetic recording medium is integrated with awrite magnetic head for writing information into the magnetic recordingmedium.

[0029] According to the sixth aspect of the present invention, providedis a magnetic apparatus equipped with a read/write magnetic head inwhich a read magnetic head comprising the magnetic sensor according tothe first aspect for reading information stored in a magnetic recordingmedium is integrated with a write magnetic head for writing informationinto the magnetic recording medium.

[0030] In a magnetic sensor having a CPP structure of the presentinvention, the opposing surface of one terminal has a size including afilm surface of a magnetosensitive film, whereas the opposing surface ofthe other terminal is smaller than and included in this film surface.The size of a portion of the magnetosensitive film through which acurrent flows, i.e., the size of a CPP portion is substantiallyindependent of the size of the opposing surface of one terminal as alarger terminal, and primarily defined by the size of the opposingsurface of the other terminal as a smaller terminal. So, determiningthis size presumably substantially uniquely determines the output value.Accordingly, even when the size of the opposing surface of one terminalis formed to be the same as or larger than the film surface, the outputvalue is not substantially influenced. When one terminal is set in thisway, the two terminals need not be aligned with high accuracy and can beformed very easily. Additionally, a desired high output value can beobtained by forming (the opposing surface) of the other terminal into avery small size.

[0031] Furthermore, in the present invention the other terminal has apredetermined shape whose width in a section perpendicular to the filmsurface and parallel to a magnetic sensitive surface changes from oneportion to another in the section. More specifically, the predeterminedshape is a relatively simple shape such as a triangle, a trapezoid, or acircle. Also, the magnetic sensitive surface is polished during themanufacture. Since the polishing amount and the element width uniquelycorrespond to each other, it is possible to easily and accuratelycontrol a desired fine element width depending on this shape.

[0032] The present invention realizes a magnetic sensor which uses a CPPstructure and is yet readily processible and which includes asubstantially accurate fine CPP structure in accordance with a desiredoutput.

[0033] Furthermore, the shape and dimensions of a CPP portion can beaccurately controlled to desired fine values. This can further increasethe output and improve the characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034]FIG. 1 is a schematic perspective view showing only the majorcomponents of a magnetic sensor according to the first embodiment of thepresent invention;

[0035]FIGS. 2A to 2D are schematic plan views showing a manufacturingprocess of the magnetic sensor of the first embodiment in the order ofmanufacturing steps;

[0036]FIGS. 3A to 3D are schematic plan views showing a manufacturingprocess of the magnetic sensor of the first embodiment in the order ofmanufacturing steps, subsequent to FIG. 2D;

[0037]FIGS. 4A to 4D are schematic plan views showing a manufacturingprocess of the magnetic sensor of the first embodiment in the order ofmanufacturing steps, subsequent to FIG. 3D;

[0038]FIGS. 5A to 5D are schematic sectional views showing amanufacturing process of the magnetic sensor of the first embodiment inthe order of manufacturing steps;

[0039]FIGS. 6A to 6D are schematic sectional views showing amanufacturing process of the magnetic sensor of the first embodiment inthe order of manufacturing steps, subsequent to FIG. 5D;

[0040]FIGS. 7A to 7D are schematic sectional views showing amanufacturing process of the magnetic sensor of the first embodiment inthe order of manufacturing steps, subsequent to FIG. 6D;

[0041]FIG. 8 is a schematic perspective view showing only the majorcomponents of a magnetic sensor according to the second embodiment ofthe present invention;

[0042]FIGS. 9A and 9B are schematic plan views showing a manufacturingprocess of the magnetic sensor of the second embodiment in the order ofmanufacturing steps;

[0043]FIG. 10 is a schematic perspective view showing only the majorcomponents of a magnetic sensor according to the third embodiment of thepresent invention;

[0044]FIG. 11 is a schematic perspective view showing only the majorcomponents of another magnetic sensor according to the third embodiment;

[0045]FIG. 12 is a schematic side view showing the major components of ahard disk drive according to the fourth embodiment of the presentinvention;

[0046]FIG. 13 is a schematic plan view showing the main components ofthe hard disk drive according to the fourth embodiment; and

[0047]FIG. 14 is a schematic side view showing the main components of acomposite magnetic head viewed from an ABS surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Hereinafter, preferred embodiments of the present invention willbe described in detail with reference to the accompanying drawings.

[0049] (First Embodiment)

[0050] This embodiment exemplifies the construction of a magnetic sensorhaving a CPP structure in which a sense current is supplied in adirection containing at least a component perpendicular to the filmsurfaces of a magnetosensitive film, and a method of manufacturing thesensor.

[0051]FIG. 1 is a schematic perspective view showing only the maincomponents of the magnetic sensor according to this embodiment.

[0052] This magnetic sensor includes a magnetosensitive film 2 forsensing an external magnetic field, a cover layer 3 which is made of Ruor the like and covers the magnetosensitive film 2, and a pair of lowerand upper terminal layers 1 and 7. These lower and upper terminal layers1 and 7 vertically sandwich the magnetosensitive film 2 and supply acurrent in a direction perpendicular to the film surfaces (opposingsurfaces 2 a and 2 b) of this magnetosensitive film 2.

[0053] The magnetosensitive film 2 can be a multilayer GMR film, a spinvalve film, a coercive force difference type multilayer film, or thelike. In this embodiment, the cover film 3 is formed on thismagnetosensitive film 2. However, the upper terminal layer 7 is, ofcourse, magnetically in contact with (magnetically connected to) themagnetosensitive film 2 via the cover film 3.

[0054] In this embodiment, the lower terminal layer 1, themagnetosensitive film 2, and the cover film 3 are simultaneouslypatterned into substantially the same size. An opposing surface 1 a ofthe lower terminal layer 1, which opposes the magnetosensitive film 2 issubstantially superposed on the opposing surface 2 a of themagnetosensitive film 2.

[0055] An opposing surface 7 a of the upper terminal layer 7, whichopposes the magnetosensitive film 2 is formed into a shape which issmaller than and included in the opposing surface 2 b of themagnetosensitive film 2.

[0056] In this magnetic sensor, the size of a portion of themagnetosensitive film 2 through which a current passes, i.e., the sizeof a CPP portion is substantially independent of the size of the lowerterminal layer 1 as a larger terminal. That is, the size of this CPPportion is defined by the size of the opposing surface 7 a of the upperterminal layer 7 as a smaller terminal. Therefore, the output value ispresumably substantially uniquely determined by determining the size ofthe opposing surface 7 a. Strictly speaking, however, the size of theCPP portion is not determined only by the size of the opposing surface 7a. This CCP portion is probably larger by a few % than the opposingsurface 7 b when the specific resistances and thicknesses of the upperand lower terminal layers 7 and 1 and the magnetosensitive film 2 andthe influence of the lower terminal layer 1 are taken intoconsideration. However, an error to this extent is within a negligiblerange, so it is reasonable to regard the opposing surface 2 b as havingsubstantially the same size as the CPP portion.

[0057] In this structure, the width and height of the opposing surface 7a of the upper terminal layer 7 are the core width and height (shown asCORE WIDTH and HEIGHT in FIG. 1 for convenience) of a common magnetichead for read. The optical core width and effective core width of acommon read magnetic head have a slight difference. When this isconsidered, the method of defining the CPP portion in this embodiment isproper.

[0058] Accordingly, even when the opposing surface 1 a of the lowerterminal layer 1 is formed into the same size as the opposing surface 2a of the magnetic sensitive layer 2 as described above, the output valueis substantially not influenced. Since the lower terminal layer 1 isdesigned in this way, the two terminals need not be aligned with highaccuracy and hence can be formed very easily. In addition, a desiredhigh output value can be obtained because the opposing surface 7 b ofthe upper terminal layer 7 is formed into a very small size.

[0059] Although the cover layer 3 is used in this embodiment, it is notan essential component and need not be used if unnecessary.

[0060] A method of manufacturing the magnetic sensor according to thisembodiment will be described below.

[0061]FIGS. 2A to 7D are schematic plan and sectional views showing amanufacturing process of this sensor in the order of manufacturingsteps. FIGS. 5A to 7D show sections taken along broken lines I-I′ inFIGS. 2A to 4D, respectively.

[0062] First, as shown in FIGS. 2A and 5A, a lower terminal layer 1 isformed using Cu, NiFe, or the like, a magnetosensitive film 2 is formedby stacking CoFe/Cu or the like, and a cover layer 3 is formed using Ruor the like, in the order named.

[0063] Subsequently, as shown in FIGS. 2B and 5B, the cover layer 3 iscoated with a photoresist 4, and this photoresist 4 is processed into adesired shape by photolithography.

[0064] As shown in FIGS. 2C and 5C, the photoresist 4 is used as a maskto pattern continuously the lower terminal layer 1, the magnetosensitivefilm 2, and the cover layer 3 by ion milling or reactive ion etching(RIE).

[0065] As shown in FIGS. 2D and 5D, the photoresist 4 is removed usingan organic solvent or a stripping solution. More favorable removal ispossible when ashing or the like is additionally performed.

[0066] As shown in FIGS. 3A and 6A, an insulating layer 5 made of, e.g.,SiO₂ is formed on the entire surface so as to cover the patterned lowerterminal layer 1, magnetosensitive film 2, and cover layer 3.

[0067] As shown in FIGS. 3B and 6B, the insulating layer 5 is coatedwith a photoresist 6, and this photoresist 6 is patterned byphotolithography. More specifically, the photoresist 6 is processed intoa shape including at least the underlying lower terminal layer 1,magnetosensitive film 2, and cover layer 3 and having a hole 6 a in asubstantially central portion.

[0068] Subsequently, as shown in FIGS. 3C and 6C, this photoresist 6 isused as a mask and the cover layer 3 as an etching stopper to patternonly the insulating layer 5 by ion milling or RIE. Consequently, theinsulating layer 5 remains in the form of an island, and a hole 5 a inwhich a portion of the cover layer 3 is exposed is formed in asubstantially central portion.

[0069] As shown in FIGS. 3D and 6D, the photoresist 6 is removed usingan organic solvent or a stripping solution. More favorable removal ispossible when ashing or the like is additionally performed.

[0070] As shown in FIGS. 4A and 7A, an upper terminal layer 7 made of,e.g., Cu or NiFe is formed to cover the entire surface.

[0071] As shown in FIG. 4B and 7B, a photoresist 8 is formed on theupper terminal layer 7 and processed into a desired shape byphotolithography.

[0072] As shown in FIGS. 4C and 7C, this photoresist 8 is used as a maskto pattern the upper terminal layer 7 by ion milling or reactive ionetching (RIE).

[0073] As shown in FIGS. 4D and 7D, the photoresist 8 is removed usingan organic solvent or a stripping solution. More favorable removal ispossible when ashing or the like is additionally performed.

[0074] Through the above process, the magnetosensitive film 2 is broughtinto magnetic contact with the lower terminal layer 1, since theopposing surface 2 a as a lower surface in FIG. 7D substantiallyoverlaps the opposing surface 1 a of the lower terminal layer 1. Inaddition, the magnetosensitive film 2 is brought into magnetic contactwith the upper terminal layer 7 via the cover layer 3, because theopposing surface 7 a of the upper terminal layer 7 is included in theopposing surface 2 b as an upper surface in FIG. 7D. As describedpreviously, a CPP portion is defined principally by the opposing surface7 a of the upper terminal layer 7 (and that portion of the opposingsurface 2 b, which opposes this opposing surface 7 a).

[0075] In this embodiment as described above, the lower terminal layer1, the magnetosensitive film 2, and the cover layer 3 are formed byperforming patterning once. Therefore, the basic configuration of themagnetic sensor can be manufactured by performing a series of patterningsteps, including film formation, resist formation, film processing, andresist removal, only three times. In contrast, to form the lowerterminal layer such that its opposing surface is smaller than theopposing surface of the magnetosensitive film, the series of patterningsteps must be further performed at least four times. Additionally, inthis case an extremely high accuracy is required in alignment of theupper and lower terminal layers. In this embodiment, however, the upperand lower terminal layers 7 and 1 and the magnetosensitive film 2 havelarger areas than the hole 5 a. This eliminates the need for highaccuracy, so an accuracy obtained by a common exposure apparatus(stepper) is satisfactory.

[0076] The size of the lower terminal layer 1 has almost no influence ondefinition of the CPP portion. Therefore, the manufacturing method ofthis embodiment can greatly reduce the number of manufacturing steps andsimplify the manufacturing steps, and contributes to implementation of ahigh-performance, fine magnetic sensor.

[0077] As has been explained above, this embodiment can implement amagnetic sensor which uses a CCP structure and is yet readilyprocessible and which includes a substantially accurate fine CPPstructure in accordance with a desired output.

[0078] (Second Embodiment)

[0079] In this embodiment, a magnetic sensor having a CPP structuresimilar to that of the first embodiment will be explained. Thedifference from the first embodiment is in shape of an upper terminallayer.

[0080]FIG. 8 is a schematic perspective view showing only the majorcomponents of a magnetic sensor according to this embodiment.

[0081] In this magnetic sensor, an upper terminal layer 11 has apredetermined shape whose width in section perpendicular to an opposingsurface 2 b and parallel to a magnetic sensitive surface 2 c of amagnetosensitive film 2 changes from one portion to another in section.More specifically, this predetermined shape is preferably a relativelysimple shape such as a triangle, a trapezoid, or a circle. In thisembodiment, a triangular shape is used.

[0082] In the manufacturing process of this magnetic sensor, the elementwidth (shown as CORE WIDTH in FIG. 8) of the magnetosensitive film 2exposed in the magnetic sensitive surface 2 c can be controlled to adesired very small value.

[0083] More specifically, as shown in FIG. 9A, a lower terminal layer 1,a magnetic sensitive layer 2, a cover layer 3, an insulating layer 5,and an upper terminal layer 7 are formed by patterning through a processsimilar to that of the first embodiment.

[0084] As shown in FIG. 9B, the resultant structure is roughly polishedalong a broken line II-II′ until the portion corresponding to this lineis exposed.

[0085] Subsequently, as shown in FIGS. 8 and 9B, the section is furtherprecisely polished.

[0086] Since the polishing amount and the element width uniquelycorrespond to each other, a desired fine element width depending on thistriangular shape can be easily and accurately controlled.

[0087] In effect, in the above first embodiment it is difficult todecrease further the size of a hole 6 a in the photoresist 6 in order toform a hole 5 a in the insulating layer 5. For example, even for ani-line stepper capable of achieving a line width of 0.25 μm in theformation of lines and spaces, about 0.4 μm is probably a limit in theformation of fine holes.

[0088] In this embodiment, however, it is readily possible, by polishingthe upper terminal layer 11 having the above shape, to achieve anelement width of 0.2 μm or less (0.2 μm is shown in FIG. 9B) exceedingthe exposure limit in hole formation.

[0089] If the upper terminal layer 7 has a predetermined shape whosewidth in section perpendicular to the opposing surface 2 b and parallelto the magnetic sensitive surface 2 c of the magnetosensitive film 2remains unchanged regardless of a portion in section as in the firstembodiment described above, such a fine element width as in thisembodiment is probably difficult to achieve. However, the above firstembodiment has the advantage that no such processing accuracy as in thisembodiment is necessary in the formation of the upper terminal layer 7.

[0090] As has been explained above, this embodiment can implement amagnetic sensor which uses a CPP structure and is yet readilyprocessible and which includes a substantially accurate fine CPPstructure in accordance with a desired output.

[0091] Furthermore, the shape and dimensions of the CPP portion can beaccurately and desirably controlled.

[0092] (Third Embodiment)

[0093] This embodiment exemplifies magnetic sensors having a CPPstructure analogous to that of the first embodiment. The difference fromthe first embodiment is in that these magnetic sensors have a magneticdomain control function and a bias application function.

[0094]FIGS. 10 and 11 are schematic perspective views showing only themain components of the magnetic sensors according to this embodiment.

[0095] In the magnetic sensor shown in FIG. 10, a magnetosensitive film2 and a cover film 3 are made smaller than a lower terminal layer 1. Afilm 12 having a magnetic domain control function is formed to beconnected to the magnetosensitive film 2 and the cover film 3 in twoside portions on the lower terminal layer 1.

[0096] In the magnetic sensor shown in FIG. 11, a magnetosensitive film2 and a cover film 3 are made smaller than a lower terminal layer 1. Afilm 13 having a bias application function is formed to be connected tothe magnetosensitive film 2 and the cover film 3 in one end portion onthe lower terminal layer 1.

[0097] To manufacture these magnetic sensors, after the lower terminallayer 1 is formed by patterning, the magnetosensitive film 2 and thecover film 3 are patterned. In this patterning, it is also possible toform previously an Au film or the like on the surface of the lowerterminal layer 1 and use this Au film or the like as an etching stopper.After the film 12 having a magnetic domain control function or the film13 having a bias application function is patterned, an insulating layer5 and an upper terminal layer 7 are patterned in the same manner as inthe first embodiment.

[0098] The material of the film 12 having a magnetic domain controlfunction and the film 13 having a bias application function ispreferably a hard magnetic material or an antiferromagnetic material.

[0099] When a magnetic sensor is actually applied to a read magnetichead, the above functions are often required.

[0100] When this is the case, the upper and lower terminal layers 7 and1 are partially or entirely formed by a soft magnetic material to allowthese upper and lower terminal layers 7 and 1 to function also asmagnetic shielding layers. Consequently, the magnetic shielding spacingcan be greatly decreased in comparison with the conventional CIPmagnetic head.

[0101] (Fourth Embodiment)

[0102] This embodiment exemplifies a magnetic apparatus equipped with acomposite magnetic head obtained by integrating a read magnetic head forreading out stored information from an information storage medium and awrite magnetic head (an inductive head). The read magnetic head is oneof the magnetic sensors described in the first to third embodiments. Inthis embodiment, this magnetic apparatus will be described by taking ahard disk drive using a hard disk as an information storage medium as anexample.

[0103]FIG. 12 is a schematic side view showing the major components ofthe hard disk drive according to this embodiment. FIG. 13 is a schematicplan view showing the main components of this hard disk drive.

[0104] This hard disk drive 20 comprises a slider 21 for holding acomposite magnetic head, a head supporting mechanism 22 for supportingthe slider 22, an actuator 23 for tracking a read magnetic head via thehead supporting mechanism 22, and a disk driving motor 24 for rotating adisk 31. The head supporting mechanism 22 includes an arm 41 and asuspension 42.

[0105]FIG. 14 is a schematic side view showing the main components ofthe composite magnetic head viewed from an ABS surface 32.

[0106] This composite magnetic head is formed by stacking a readmagnetic head 51 which is one of the magnetic sensors described in thefirst to third embodiments, and a write magnetic head 52. Morespecifically, upper and lower shielding layers 61 and 62 serving asmagnetic shields are formed above and below the read magnetic head 51.Lower and upper poles 63 and 64 constituting the write magnetic head 52are formed in this order on the upper shielding layer 61. These membersare formed in an aluminum protective layer 65 to construct the compositemagnetic head.

[0107] In this composite magnetic head, a magnetic sensitive surface 2Cis an ABS surface, and the core width and height are defined as shownin, e.g., FIGS. 1 and 8.

[0108] The disk driving motor 24 rotates the disk 31 at a predeterminedspeed. In order for the composite magnetic head to access apredetermined data track on the disk 31, the actuator 23 moves theslider 21 holding this composite magnetic head in the radial directionacross the surface of the disk 31. This actuator 23 is typically alinear or rotary voice coil motor.

[0109] The slider 21 is, e.g., an air bearing slider. When the hard diskdrive 20 is activated or stopped, this slider 21 comes into contact withthe surface of the disk 31. When information is to be reproduced fromthe hard disk drive 20, the slider 21 is kept on the surface of the disk31 by an air bearing formed between the rotating disk 31 and the slider21. The read magnetic head held by the slider 21 writes information inand reads out information from the disk 31.

[0110] This embodiment can implement a magnetic sensor which uses a CCPstructure and is yet readily processible and which includes asubstantially accurate fine CPP structure in accordance with a desiredoutput. Also, by constructing a hard disk drive by using this magneticsensor as a read magnetic head of a composite magnetic head for writingand reading out information, this embodiment can achieve a highrecording density and further miniaturize the apparatus.

[0111] Indeed, use of a hard disk drive in which a magnetic sensoraccording to, e.g., the second embodiment is employed as the readmagnetic head sufficiently meets a high density recording more than 100Gbits/in².

[0112] In this embodiment, the magnetic sensor described in any one ofthe first to third embodiments is used as a read magnetic head of acomposite magnetic head. However, this magnetic sensor can also be usedas a separate read magnetic head.

[0113] -Experimental Result-

[0114] Various experimental results for explaining the present inventionin more detail will be given below.

(Experimental Example 1)

[0115] The magnetic sensor described in the first embodiment wasmanufactured under the following conditions, and its resistance valueand resistance change amount were measured.

[0116] Lower terminal layer (Cu: 500 nm), magnetosensitive film (CoFe:11 nm/Cu: 21 nm×10), cover layer (Ru: 5 nm), insulating layer (SiO₂: 50nm), and upper terminal layer (Cu: 500 nm)

[0117] When the magnetic sensor was manufactured as above, the shape ofa CPP portion was a square of 1× 1 μm². This magnetic sensor had aresistance value of 15 mΩ and a resistance change amount of 2.5 mΩ.

[0118] Subsequently, as described in the second embodiment, the sectionof this magnetic sensor was polished to form the upper terminal layerinto a triangular shape so that the element width of the CPP portion was0.2 μm.

[0119] The resultant magnetic sensor had a resistance value of 1,500 mΩand a resistance change amount of 120 mΩ (note that after the sectionpolishing a large resistance value was detected because the measurementwas done by using a two-terminal method).

(Experimental Example 2)

[0120] The magnetic sensor described in the first embodiment wasmanufactured under the following conditions, and its resistance valueand resistance change amount were measured.

[0121] Lower terminal layer (NiFe: 100 nm/Cu: 10 nm), magnetosensitivefilm (CoFe: 11 nm/Cu: 21 nm×10), cover layer (Ru: 5 nm), insulatinglayer (SiO₂: 50 nm), and upper terminal layer (Cu: 10 nm/NiFe: 50 nm)

[0122] When the magnetic sensor was manufactured as above, the shape ofa CPP portion was a square of 1× 1 μm². This magnetic sensor had aresistance value of 20 mΩ and a resistance change amount of 2.4 mΩ.

[0123] Subsequently, as described in the second embodiment, the sectionof this magnetic sensor was polished to form the upper terminal layerinto a triangular shape so that the element width of the CPP portion was0.2 μm.

[0124] The resultant magnetic sensor had a resistance value of 3,000 mΩand a resistance change amount of 115 mΩ.

What is claimed is:
 1. A magnetic sensor comprising: a magnetosensitivefilm for sensing an external magnetic field; and a pair of terminalsthat vertically sandwich said magnetosensitive film for applying anelectric current to said magnetosensitive film in a directionperpendicular to a film surface of said magnetosensitive film, one ofsaid terminals having a surface that is opposed to said magnetosensitivefilm so as to include the whole area of said film surface, while theother of said terminals having a surface that is smaller in area thansaid film surface and opposed to said magnetosensitive film so as tofall within the area of said film surface.
 2. The sensor according toclaim 1 , wherein said surface of said one of said terminals is largerin area than said film surface.
 3. The sensor according to claim 2 ,further comprising a magnetic domain control member on at least one sidein width of said magnetosensitive film.
 4. The sensor according to claim2 , further comprising a magnetic bias applying member on one side inheight of said magnetosensitive film.
 5. The sensor according to claim 1, wherein said other of said terminals has a predetermined shape in asection perpendicular to said film surface and parallel to amagnetosensitive surface, said shape having its width changing from oneportion to another.
 6. The sensor according to claim 1 , wherein saidother of said terminals has a predetermined shape in a sectionperpendicular to said film surface and parallel to a magnetosensitivesurface, said shape having a uniform width.
 7. The sensor according toclaim 1 , wherein one of said terminals and part or the whole of theother of said terminals are made of a magnetic shielding material.
 8. Amanufacturing method of a magnetic sensor comprising a magnetosensitivefilm for sensing an external magnetic field, and a pair of terminalsthat vertically sandwich said magnetosensitive film for applying anelectric current to said magnetosensitive film in a directionperpendicular to a film surface of said magnetosensitive film, saidmethod comprising the steps of: forming one of said terminals such thata surface of it is opposed to said magnetosensitive film so as toinclude the whole area of said film surface; and forming the other ofsaid terminals such that a surface of it is smaller in area than saidfilm surface and opposed to said magnetosensitive film so as to fallwithin the area of said film surface.
 9. The method according to claim 8, wherein said surface of said one of said terminals is formed to belarger in area than said film surface.
 10. The method according to claim9 , wherein said magnetic sensor further comprises a magnetic domaincontrol member on at least one side in width of said magnetosensitivefilm.
 11. The method according to claim 9 , wherein said magnetic sensorfurther comprises a magnetic bias applying member on one side in heightof said magnetosensitive film.
 12. The method according to claim 8 ,wherein said other of said terminals is formed to have a predeterminedshape in a section perpendicular to said film surface and parallel to amagnetosensitive surface, said shape having its width changing from oneportion to another.
 13. The method according to claim 8 , wherein saidother of said terminals is formed to have a predetermined shape in asection perpendicular to said film surface and parallel to amagnetosensitive surface, said shape having a uniform width.
 14. Themethod according to claim 8 , wherein one of said terminals and part orthe whole of the other of said terminals are made of a magneticshielding material.
 15. A manufacturing method of a magnetic sensor inwhich a magnetosensitive film for sensing an external magnetic field isvertically sandwiched by a pair of terminals to apply an electriccurrent to said magnetosensitive film in a direction perpendicular to afilm surface of said magnetosensitive film, said method comprising thesteps of: forming one of said terminals such that a surface of it isopposed to said magnetosensitive film so as to include the whole area ofsaid film surface; forming the other of said terminals such that asurface of it is smaller in area than said film surface and opposed tosaid magnetosensitive film so as to fall within the area of said filmsurface, and said other of said terminals has a predetermined shape in asection perpendicular to said film surface and parallel to amagnetosensitive surface, said shape having its width changing from oneportion to another; and polishing an end surface that is to serve assaid magnetosensitive film, so as to control the width of said other ofsaid terminals exposed on said end surface.
 16. The method according toclaim 15 , wherein said surface of said one of said terminals is formedto be larger in area than said film surface.
 17. The method according toclaim 16 , wherein said magnetic sensor further comprises a magneticdomain control member on at least one side in width of saidmagnetosensitive film.
 18. The method according to claim 16 , whereinsaid magnetic sensor further comprises a magnetic bias applying memberon one side in height of said magnetosensitive film.
 19. The methodaccording to claim 15 , wherein one of said terminals and part or thewhole of the other of said terminals are made of a magnetic shieldingmaterial.
 20. A manufacturing method of a magnetic sensor in which amagnetosensitive film for sensing an external magnetic field isvertically sandwiched by a pair of terminals to apply an electriccurrent to said magnetosensitive film in a direction perpendicular to afilm surface of said magnetosensitive film, said method comprising thesteps of: forming one of said terminals such that a surface of it isopposed to said magnetosensitive film so as to include the whole area ofsaid film surface; forming the other of said terminals such that asurface of it is smaller in area than said film surface and opposed tosaid magnetosensitive film so as to fall within the area of said filmsurface, and said other of said terminals is formed to have apredetermined shape in a section perpendicular to said film surface andparallel to a magnetosensitive surface, said shape having a uniformwidth; and polishing an end surface that is to serve as saidmagnetosensitive film, so as to control the width of said other of saidterminals exposed on said end surface.
 21. The method according to claim20 , wherein said surface of said one of said terminals is formed to belarger in area than said film surface.
 22. The method according to claim21 , wherein said magnetic sensor further comprises a magnetic domaincontrol member on at least one side in width of said magnetosensitivefilm.
 23. The method according to claim 21 , wherein said magneticsensor further comprises a magnetic bias applying member on one side inheight of said magnetosensitive film.
 24. The method according to claim20 , wherein one of said terminals and part or the whole of the other ofsaid terminals are made of a magnetic shielding material.
 25. A readmagnetic head comprising a magnetic sensor for reading informationstored in a magnetic recording medium, said sensor comprising: amagnetosensitive film for sensing an external magnetic field; and a pairof terminals that vertically sandwich said magnetosensitive film forapplying an electric current to said magnetosensitive film in adirection perpendicular to a film surface of said magnetosensitive film,one of said terminals having a surface that is opposed to saidmagnetosensitive film so as to include the whole area of said filmsurface, while the other of said terminals having a surface that issmaller in area than said film surface and opposed to saidmagnetosensitive film so as to fall within the area of said filmsurface.
 26. The head according to claim 25 , wherein said surface ofsaid one of said terminals is larger in area than said film surface. 27.The head according to claim 26 , wherein said magnetic sensor furthercomprises a magnetic domain control member on at least one side in widthof said magnetosensitive film.
 28. The head according to claim 26 ,wherein said magnetic sensor further comprises a magnetic bias applyingmember on one side in height of said magnetosensitive film.
 29. The headaccording to claim 25 , wherein said other of said terminals has apredetermined shape in a section perpendicular to said film surface andparallel to a magnetosensitive surface, said shape having its widthchanging from one portion to another.
 30. The head according to claim 25, wherein said other of said terminals has a predetermined shape in asection perpendicular to said film surface and parallel to amagnetosensitive surface, said shape having a uniform width.
 31. Thehead according to claim 25 , wherein one of said terminals and part orthe whole of the other of said terminals are made of a magneticshielding material.
 32. A read/write magnetic head in which a readmagnetic head comprising a magnetic sensor for reading informationstored in a magnetic recording medium is integrated with a writemagnetic head for writing information into said magnetic recordingmedium, said sensor comprising: a magnetosensitive film for sensing anexternal magnetic field; and a pair of terminals that verticallysandwich said magnetosensitive film for applying an electric current tosaid magnetosensitive film in a direction perpendicular to a filmsurface of said magnetosensitive film, one of said terminals having asurface that is opposed to said magnetosensitive film so as to includethe whole area of said film surface, while the other of said terminalshaving a surface that is smaller in area than said film surface andopposed to said magnetosensitive film so as to fall within the area ofsaid film surface.
 33. The head according to claim 32 , wherein saidsurface of said one of said terminals is larger in area than said filmsurface.
 34. The head according to claim 33 , wherein said magneticsensor further comprises a magnetic domain control member on at leastone side in width of said magnetosensitive film.
 35. The head accordingto claim 33 , wherein said magnetic sensor further comprises a magneticbias applying member on one side in height of said magnetosensitivefilm.
 36. The head according to claim 32 , wherein said other of saidterminals has a predetermined shape in a section perpendicular to saidfilm surface and parallel to a magnetosensitive surface, said shapehaving its width changing from one portion to another.
 37. The headaccording to claim 32 , wherein said other of said terminals has apredetermined shape in a section perpendicular to said film surface andparallel to a magnetosensitive surface, said shape having a uniformwidth.
 38. The head according to claim 32 , wherein one of saidterminals and part or the whole of the other of said terminals are madeof a magnetic shielding material.
 39. A magnetic apparatus equipped witha read/write magnetic head in which a read magnetic head comprising amagnetic sensor for reading information stored in a magnetic recordingmedium is integrated with a write magnetic head for writing informationinto said magnetic recording medium, said sensor comprising: amagnetosensitive film for sensing an external magnetic field; and a pairof terminals that vertically sandwich said magnetosensitive film forapplying an electric current to said magnetosensitive film in adirection perpendicular to a film surface of said magnetosensitive film,one of said terminals having a surface that is opposed to saidmagnetosensitive film so as to include the whole area of said filmsurface, while the other of said terminals having a surface that issmaller in area than said film surface and opposed to saidmagnetosensitive film so as to fall within the area of said filmsurface.
 40. The apparatus according to claim 39 , wherein said surfaceof said one of said terminals is larger in area than said film surface.41. The apparatus according to claim 40 , wherein said magnetic sensorfurther comprises a magnetic domain control member on at least one sidein width of said magnetosensitive film.
 42. The apparatus according toclaim 40 , wherein said magnetic sensor further comprises a magneticbias applying member on one side in height of said magnetosensitivefilm.
 43. The apparatus according to claim 39 , wherein said other ofsaid terminals has a predetermined shape in a section perpendicular tosaid film surface and parallel to a magnetosensitive surface, said shapehaving its width changing from one portion to another.
 44. The apparatusaccording to claim 39 , wherein said other of said terminals has apredetermined shape in a section perpendicular to said film surface andparallel to a magnetosensitive surface, said shape having a uniformwidth.
 45. The apparatus according to claim 39 , wherein one of saidterminals and part or the whole of the other of said terminals are madeof a magnetic shielding material.